Selective signaling system



1927 G. w. FLYNN SELECTIVE S I GNALING SYSTEM I Filed March 2. 1921 4 Cm m mmr WEE-.

Patented Aug. 9, 1927.

nniran stares earsur orrics.

GEORGE WILLIAM FLYNN, OF BLUNDELLSANDS, NEAR LIVERPOOL, ENGLAND.

SELECTIVE SIGNALING SYSTEM.

7 Application filed March 2, 1921, Serial No. 449,103, and in GreatBritain July 4, 1919.

(GRANTED UNDER THE, PROVISIONS 01? THE ACT OF MARCH 3, 1921, 41 STAT. L,1313.)

The present invention relates to electric signaling systems such as areused for selectively signaling one or more stations connected to acommon line or so called omni bus circuit. Y

A considerable diificulty has been experienced hitherto in selectingstations where the number of these connected to one lineis large, say inthe neighborhood or 100, and consequently the equipment installed, hasbeen proved to be either'unduly expensive on account of the intricatenature of the apparatus or has failed to give satisfactory and reliableresults under the exceptionally adverse conditions of working to whichsuch systems are subjected.

The object of the. present invention is to provide simplified apparatusat each out-station and at the control station which will be reliableand satisfactory and at the same time will enable the number of stationsto be increased up to say, a hundred, without any ad ditional featuresin the substation apparatus.

According to the invention, the out-stations are selected by means of anumber of independent series of impulses which may be produced by the,agency of a dial-switch of identical construction with those used inautomatic telephone systems, operated at the signaling or controlstation. The out-stations are provided with a selective device such as arotary or like switch in which a driving magnet causes a wiper tosuccessively pass over and make contact with a series or bank ofcontacts. Each out-station is identical except for simple connections tocertain contacts which connections are pe culiar to the station, andalso other similar connections peculiar to eithera group or to the wholeof the stations if it is desired to ring up either a particular group ortwhole of the stations at once.

Each station will be numbered, usually in the decimal notation, tocorrespond to the ten impulses sent by the well knowndial switch. Then,if there are not more than a hundred stations which will usually be thecase, only two digits would be dialled. The dialling of the tens digitwould cause the switches at every station to operate, but in digit.

only ten cases would the wiper rest on a contact which was connected upso as to prepare a circuit in order that the bell to be selected may berung on the dialling of the units This next dialling then eitects asecond operation at each of these ten stations and preferably thefurther operation ofthe switches already operated. This next dial lingmoves ,the wiper to another contact which only in the case of thestation required, will be connected up to complete the operation andeffect the ringing of the bell.

Arrangements are provided for enabling the out-station to ring up the.control station, also a means is incorporated of letting the controlstation know when the bell at the out-station selected is ringing inresponse to the operation of dialling.

Further details of the invention will be better understood by referringto the accompanying drawings which illustrate one meth 0d of carryingout the invention by way of example. Fig. 1 shows diagrammaticallythe'c0nn6ctions' of the apparatus at the control station and the outstations, Fig. 2 shows diagrammatically one form of dial switchemployed.

The apparatus at station C which is the. calling or control station, isprovided with a speaking or ringing key 1, through which the operatorsinstruments are connected to the line A B. An impulse relay 5 is adaptedto be connected through the springs 6 and 7 of key 1 with the circuitbattery 150, a dial switch or calling device 3 of the type usually usedon automatic telephones being connected with itscontact springs 3 and 3in series with the relay 5 and battery 150. The construction of the dialswitch 3 is more particularly shown in Fig. 2. The relay 5 functions toreverse the polarity of the battery 4 on each interruption of thecurrent passing through the relay5 by the dial switch 3. To prevent theoutgoing impulses being overheard by the operator the dial' switch 3 isprovided with an auxiliary pair of springs 59 arranged to short circuitthe winding 57 of induction coil 58 when the dial is ofi' normal due tothe sending of the impulses. I

The speaking sine of the key 1 is connected to the line A B throughspring 8, wire 71, spring 72 and also through spring 19, spr' m 79, wire79 and spring 78. The speaking set comprises receiver 76. induction coil58 having windings 57, 74. 75 and 8 1, transter 85, cut out switch. S3,and inductive resistance 86.

A hell 9? and line ianip 95 are connected lso to the line A when thesprings oi the speaking side are in normal position, by the followingarrangement Springs 89. 91 of key 1, sensitive line relay 90. whichlatter operates to complete the circuitof relay 92 through earth.battery, springs 81 and 9;: ct key 1, contact lamp 955. relay to earthand also associated circuit 01" hell 9?.

At each out sta on D. F, a. polarized relay is connected across the lineA B through normally closed springs 21, 22 02" key 20", noninductiveresistance 23. winding 2 1- of relay 20. springs 25. 26 of key 20 toline The relay 20 operates to close one of two circuits through contacts28 29 or 28. 82. The former closes the circuit of a slow acting relay 2?and the contacts 28, 32, when this latter circuit is closed close thecircuit of a rotary selective switch 38 through a stepping magnet 36 andholding relay in parallel.

The rotary switch 38 comprises a number or": contacts in this ctwentybne in ninnber, such as 37 forining the arc of a circle, a contactare 4.0, wiper 39 adapted to contact with the individual contacts of theare 10. The wiper is stepped around by the inipulses passing through.the electro-n'iagnet 36 which operiiites suitable stepping mechanismsuch teeth mounted on a circular plate connected with the wiper 39.Mounted on the said plate a projection 110 opted to separate pair oi"contact springs 48 when the wiper is zero position. A release magnet 69opei .ting detent holding the toothed plate ot the wiper arm 39 alsoprovided and operates as hereinafter descr bed. Associated with therotary si itch is a bus l or device 111 con'iprisiug a sin'iih r numberof terminals such as 12, 52. 101. as provided on the switch 38. a tensbar and u bar Each at t e contacts of the rotary switch 38 is connectedto the correspc .ding terminal ot the device 111. or at least seine willbe later denuinher of the connected to 111 correspond ing to t tepsdigit and Llle tens bar is! the efore lies adjacent the first tenterminals onl The units bar 53 is connected to that terminal of thedevice 111 which corresponds to the sum of the tens u s digits theoutstation. F or example if the number of the station is the tens car atis connected a pivoted pawl. engaging with stations have terminals and 9connected by a link, if desired as also terminal and 102. Associatedwith the tens bar 4% is a circuit including contact d5 of holding relay35, relay ll" and earth. Connected with the units bar 53 is a circuitcomprising contact of relay a l, contact 46 of relay 35;. bell 55,winding 56 of relay 20 and earth. I

A speaking set including receiver and transmitter 65- is connectedacross the line A B through a switch having a plurality of springs 63,6d, 66, 67; 68 tl a. function of which will be hereinafter described Aconde; ser 61 and induction coil 62 are inserted in the circuit asshown.

It it is desired to call up the operator at station C from theoutstations D, E, F, etc, the operation of the calling key 21) connectsa ringing battery from earth through springs 88, to line A, throughoperation indicati devices. line B, springs 26, and 87 of key 2 to theearth. 7

Fig- 2 shows asuitable form of dial switch or calling device. Thiscomprises a finger plate llo'having perforations 116 and rotatablymounted ona central spindle 119. Below thcplate is a. further fixednumber plate having numbers 118 thereon from 19 and O. Pivotally mountedon the plate 115 is a pawl 121 adapted to engage the teeth of a ratchetwheel 120 capable of rotational increment about the spindle 119. Rigidlysecured to the ratchet 120 is a cam wheel provi led with a plurality ofteeth or projections corresponding to the numbers mounted on thenumber'plate.

The dial switch is provided with a pair of interrupter contact springs 3and3 and also a pair of oil norinal contact springs 59 the longer one ofwhich engages with an insulated pin 12% adapted to hold the springsoutof contact in the normal position. A linger stop 12% is rigidlysecured to the back plate 117.

To dial a number or digit the finger is inserted in the opening 116 ofthe finger plate 115 through which the required number on he numberplate 11? can be seen and the slate 113 is rotated in a clockwisedirection until the finger abuts against the stop 12 i. lly this actionthe pawl 121 carried over fi litllllbtli of teeth of the ratchet wheel120 corresponding to the number select d and tens ons. spiral or thelilre springs, (not shown) usually assembled about the spindle 119.. 9nthe releasing of the linger plate 115 the spring returns the plate toits normal position and in consequence. the movement the pawl 121rotates the ratchet wheel 120 and therewith the cam wheel spring 3" andto cause the same to break contact with the spring 3 according to thenumber dialed.

When the plate 115 is moved from its nor mal position the pin 123 beingremoved from the longer of the off normal contact springs 59 allowscontact to be made between the two which remain in contact all the timethe plate, 115 isaway from its normal position;

To ensure uniformity in the interrupt-ions.

of'contact springs 3"and 3" a suitable goveining device may beincorporated in the mechanism of the switch thereby controlling thereturn movement of the plate 115.

Referring to Figure 1 the-operators set includes a speaking and diallingkey 1, a speaking set 2, a dial switch 3 which may be of the well knowntype as used in automatic 13 of relay to positive pole of battery andthence from negative pole of battery through contacts 14 and 15 of relay5, inductances 16 and 17, contact springs 18 and 19 of key 1 to 15 line.i

it each out-station the efiect of connecting batt ry 4 to line is tooperate the polar. ized relay 20 of that station through the followingcircuit from positive pole of battery connected to line A throughsprings 21 and ofcalling key 20, through a non-inductive resistance 23,winding 24 of-relay 20, through springs 25and 26 of calling key 20 tonegative pole of battery connected to 13 line. The polarized relay 20operates in such a manner as to close the circuit of the slow releasingrelay 27 through its contacts 28 and 29. The operator at the controlstation then works the dial to send impulses to line in accordance withthe number of the .wanted party. Assume that the party wanted is number53. He null then dial 5 breaking the circuit of impulse relay 5 times.

The impulse relay allows-its armatures tofall back and reverse thepolarity of battery connected to line. aswill be seen from tracing thecircuits, line A instead"ofbeingeonnected to positive pole of battery 4through springs 12 and 13 will be connected to negative pole of ba terythrough springs 12 and- 30 and line B will similarly be connected topositive pole of battery through springs 15 and 31. p

The effect of these momentaryrev'ersals of current'i's to cause all thepolarized relays 20 connected across the line to operate so to call aparty .ner of the figure.

that the contact member 28 momentarily) makes contact with contact 32.The first impulse closes a circuit as follows: earth. contact 28 and 32of relay 20, contacts 33 and 34 of relay 27, which being slow actingwill not fall back formomentary breaks in its circuit, slow actingholding relay 35 and driving magnet 36 'inparallel, to normal' contact37 of rctaryswitch 38,- wiper 39, are 40 to cart-lied battery 1401Thedriving magnet operates to step the wiper 39 one step, which'breaksthe battery connection through contact '37, afurther connection tobattery 141 being made by means of theen tactsprings 41 of relay35-which'being of the'slow release type remains operated during thesubsequent impulses of the same series. fore due to the-contacts '28 and32 making and breaking so-many times 'cause'the driving magnet to'stpt'hewi er 39 to the fifth contact 42 from normal. Thej efi'ect of thisis to connect positive pole of battery 140 to the fifth. terminal 42inthe row of 21 terminals shown at the lower right hand cor- The 20contacts of r the rotary switch are connected to these 21 terminals byconductors as shown diagrammatically in the drawings, the twenty-firstterminal andtenth terminal being connected together for reasons to beexplained later.

Atall stations whose numbers have 5 for the first digit a wire link isprovided connecting the fifth terminal to a bus bar 44 termed a tens barwhich is placed adja: cent to the first ten terminals as shown.

Now after the first five impulses have been sent there is a slightinterval which permits the relay 35 to de-energize, allowing thecontacts45 and 46 to close and contact 41 to open.

The result of this is that the following circuit is closed in the tenstations whose first digit commences with 5, but not in any of the otherstations: battery 140, are 40, fifth contact 42?, fifth terminal 42,tens bar 44, contacts 45 of relay 35, relay 47 to earth. A circuit hadpreviously been closed through relay 47 from battery 148, off normalsprings 48 (now closed) of rotary switch resistance 49, relay 47 toearth, but

the current through this circuit while sufiicientto maintain the relay47 operated is insufficient to operate it by itself due to theresistanee49; consequently the relay 47 is o'perated-through-the firstmentioned circuit and is subsequently maintained oper-. ated'through thesecond circuit.

Theoperator" then proceeds to dial the units digit-3. the effect of the"first impulse'is' to send an impulse of current through the followingcircuit: earth, contacts 28 and 32 of polarized relay 20, contacts 33and 34 of relay 27, relay 35' and driving magnet 36 in parallel,coiiifect'i'oh'po'iii't 1-42, Contact 50 and The remaining four impulsesthere wire link on the fifth terminal which is only v present in suchstations The holding relay 35 operates as before connecting battery 1 11through contact 41 for the subsequent operation of the driving magnetlieu of that supplied through the fifth contact and wire link which isremoved on the advance of the wiper 39. The driving magnet operates tostep the wiper to the sixth contact and with the two subsequent impulsessteps it to the eighth contact 52 when the dialling being completed theholding relay 35 is deenergized. At station numbered 53 there will be asecond connecting link joining the eighth terminal 52 to a second busbar 53 placed adjacent the second to nineteenth terminals and termed theunits bar.

Consequently when the wiper rests on the eighth contact sufficientlylong for the relay 35 to be (ls-energized a circuit will be closed asfollows: battery 140, are 40, wiper 39, eighth contact 52, eighthterminal 52, wire link to units bar 53, thence through contact 0t relay47, contact 46 of relay 35, bell through a few turns 56 on polarized relay to earth. The bell rings and at the time by means of the winding 56on polarized relay 20, a current is induced on.

I ductance 10 in series with the impulse circuit.

In order to avoid the outgoing impulses being overheard by the operatorthe dial switch 3 is provided with an auxiliary pair of springs 59arranged to short circuit the winding 57 of induction coil 58 when thedial is oil normal due to impulses being sent. 7

The called party at station No. 53 hearing his bell ring, lifts hisreceiver 60 to connect his speaking set in circuit, the receiver 60,being connected across the line in series with the condenser 61 andsecondary winding of induction coil 62 by means of the switch hooksprings 63 and 64 while the transmitter 65 is connected to battery 165through the primary of induction coil 62 and switch springs 66 and 67. Acircuit is momentarily closed on lifting the receiver. from battery 165,switch springs 67 66 and 68 and release magnet 69 to earth. The releasemagnet operates to remove detent 70 from ratchet wheel of rotary switchwhich rseasso in'nnediately restores to normal; the OE normal springs 48then break contact and relay l7 de-energizes. At the same time the bellcircuit is broken. I V p The operator then noticing the cessation of theringing tone places his key 1 to the speaking position (i. e. to theleft) connecting speaking set across the line over the followingcircuit: line A, springs 8 and 71, 72 and 73 of key 1, winding 74: ofinduction coil 58, winding 75 and receiver 76 in parallel springs 77,78. 79 and 19 of key 1 The removal of current from the line causes thepolarized relays 20 at every sta- 7 tion on the line to restore to theirnormal position with the contact'QS midway between contacts 29 and 32and making contact with neither. The result is that the relay 27die-energizes. Consequently the following circuit is closed at contact80, battery 1418, of? normal springs 48, contact 80, release magnet 69to earth. It will be understood that this occurs at every station on theline, exceptthe selected station, as every rotary switch has movedeither to the rfith or the eighth contact and therefore the oil normalsprings 48 are closed;

Jpon the rotary switches v38 returning to normal, the off normal springs48 break con tact, breaking the circuit of the release magnet and alsothe circuit of the relay 47, so that every station is restored tonormal,

When the conversation is finished the called party restores his receiverto the switch hook and the operator places his key in the normalposition. it will be appreciated that in order to ring any out-stationhell it is necessary to operate the relay 17 which depends upon the tensdigit and subsequent-- .lv to operate the bell which depends upon theunits digit, and upon the operation of relay 4?. For instance, in thecase of station 62, his rotary switch will remain on the fifth contact,and will not be further oper ated, so that although the same totalnumber 0t digits are dialled, as in the typical example 53) an entirelydifferent result en sues. Similarly it will be appreciated that only oneof a hundred stations will be rung up it the cross-connecting links ateach station are arranged correctly, for instance number 11 will beconnected with 1st terminal connected to tens bar and 2nd termition toearth, The line relay is designed to respond to nal to units bar, number16 with lstterminal .to. tens bar. and 7th'terminal to units bar,

number 43 with 4Eth terminal totens bar and 7th (4+3) terminal to unitsor generally number at with a teri'ninal to tens bar and a'H/ terminalto units bar.

ator, this may be done by pressing the call ing key 20 which connectsbattery across the line through the circuit battery, springs 88 and 21of calling key 20 to line A, thence to springs 8, 71, 72, 89 of key 1,sensitive line relay 90, springs 91, 78, 79 and 19 of keyl to line ,Band thence through springs 26 and 87 of calling keyi20 of callingstathis current, while the polarized relays 20 are preferably arrangedas to be incapable of responding. Relay 90 operatesand closes thecircuit of relay 92 which locks itself over the circuit-earth, relay 92and itsc ontact 93,

springs 94 and 81 of key 1 to, battery at the same time the line lamp.95 illuminating in series with the night alarm relay 96 which is adaptedto close the circuit of the night bell 97. As soon as the controlstation operator operates his key to the speaking position the lockingcircuit of relay .92 is broken and the lamp95 is extinguished. Incertain cases it is oftendesirable for the controller toCOIHHIUIIlCEItQWltll alllthe out-stations at once or to communicate withall the stations of a given group "and this may readily be ellectedbythe following 'arrangement.

It'will be assumed first of all that the controller desires tocommunicate 'with all the stations at once, in order to efiect this thetwentieth terminal 98 of each stationis'connected by a crossconnectinglink to'an auxiliary terminal 99 adjacent with the. units bar; also thetwenty-first terminal 100 is 7 wired tothe tenth terminal lOlperinanently as shown while a cross connecting link con- 'nects it to asecond auxiliary terminal lQ2.

In order to call all the stations the controller dialsO O (Ov signifyingten impulses).

The dialling for the tensidigit issiinilar to that previouslydescribedythe *rotary switchesall being rought with their wipers 39 onthe tenth contact-.froin normal.

tens bar. the subsequent diallingcauses-the instruments to operate asp'rcVi usly de- 4" scribed with reference to the-calling of stathosestations atwhich thereis across con necting link from the tenth terminalto the v ployed a reversal of current operating a anddi'iving magnet 36in parallel, contact 50 and 103 of relay l7, terminal 102, crossconnecting link to terminal 100, thence to tenth contact of rotaryswitch, wiper 39, arc 40, to battery. Relay 35 operates and remainsoperated through the subsequent series of impulses to hold contacts .41closed so that driving magnet 36 continues torespond to the impulses atevery station, consequently on the tenth impulse of the units digit thewiper 39' comes to rest upon the twentieth contact, the followingcircuit being closed:

ear th, battery, are 40, wiper 39, twentieth cont-act to terminal 98,cross connecting link to terminal 99, contact an of relay 35, bell 55,winding 56 of relay 20 to earth. As itis only necessary for thetwentieth contact to be reached, the bells at every station will ring. I

It will be appreciated that by ieglecting to provide cross connectinglinks between terminals 98 and 9,9' or 100 and 102 at any stations thesestations may be made exceptions to the general rule.

I Similarly other group calls may be arranged by suitably connectingcertainolf the roup of terminals with the tens and units bars, inaddition to the connections appropriate to the individual numbers of therespective instruments,

and in this way groups of stations may be rung at a time.

, For instance itmay be decided that the number 53 instead of being thenumber of a station is the number of a group cal Then all stationsbelonginglto that group will have connecting links from the fifthterminal to the tens bar and from the eighth terminal to the units barpreferably the members of thegroup will all have 5 for theirjfirstdigit, this will avo d unnecessary complications.

I It w llbe appreciated that a very (ZlllClGDt select ve signalingsystem capable of dealiiig witha largenumber of stations has beenevolved, at the same time it must be understood that the invention is byno means limited to the construction described as several modificatio smay be made therein without departing I V rinongotber modifications itwill be ap- PlQClttlZQCldhtll? it is by no means essential that theimpulses should consist of reversals of'current. The reason'foremploying reversals instead of'a'direct make and break s to increase thereliab lityoi": the system, itbeing well known that for longlines onwhich the invention will usually be em polarized relay is more.efi'ective than a simple make or break. Furtherpthe arrangeoiu. thespirit of the invention. Y

ment of inductances 10, 11, 16 and 17 with the condensers 104: and 105in shunt as shown in the drawings is not essential but is desirable forthe eiiicient transmission of the impulses over a long line.

Also, it must be understood that the arrangement of batteries shown isonly conventional and it is by no means essential that there should bean earth connection at either the out station or the controllers stationas regards the battery. Further there will usually be only one or atmost two batteries at each out-station, one for the transmitter circuitand one for the driving magnet and the operating relays.

I declare that what I claim is 2- 1 1. in a selective signaling systemthe com: bination oi a central station, a plurality of outlyiin stationseach having a designation number, a common line connecting saidstations, means at'said central station to transmit over said line aplurality of series of impulses, an indicating device at each of saidoutlying stations, a rotary selective switch at each at said outlyingstations having a single rotary arm. and a plurality of contacts, meansto drive said arm in response to the first series of impulses receivedfrom said central station, an electrical. circuit at each outlyingstation connected to a contact of said rotary switch corresponding, tothe first digit of said designation number, means controlled by currentin said circuit to cause said driving means 0t said rotary arm to berectuated on the transmission of a sub sequent series of impulses and asecond electrical circuit connecting a contact or" each or said rotaryswitches corresponding to the sum of the digits of said designationnumber to said indicating device.

2- In a selective signaling system the combination of a central station,a plurality of outlying stations each having a designation number, acommonline connecting said sta tions, means at said central station totransmit over said line a plurality of series of impulses, an indicatingdevice at each of said outlying stations, a rotary selective switch ateach of said outlying stations having a single rotary arm and aplurality of contacts, means to drive said arm' in response to the firstseries of impulses received from said central station, an electricalcircuit at each outlying station connected to a contact of said rotaryswitch corresponding to the first digit of .said designation number,means controlled by current in said circuit to cause said driving meansof said rota y arm to be reactuated on the transmission oi a subsequentseries of impulses, a second electrical circuit connecting a contact oreach rotary switch corresponding to the sum of the digits of saiddesignation numberto said indicating device and means controlled by saidfirst circuit to establish a current in said second circuit on hecompletion oi transmlssion ot a succeeding series of impulses.

In a selective signaling system the combination of a central station, aplurality of outlying stations each having a designation number, acommon line connecting said stations, means at said central station totransmit over said line a plurality of series oi impulses, an indicatingdevice at each 01":

said outlying stations, a rotary selective switch at each of saidoutlying stations having a single rotary member and a plurality ofcontactsyme ans' to rotate said arm in response to the first series ofimpulses received trom said central station, an electrical circuit ateach outlying station connected to a contact of said rotary switchcorresponding to the first digit oi said designation number, a secondelectrical circuit bination of a central station, a plurality ofoutlying stations each having a designation number, a common lineconnecting said stations, means at said central station to transmit oversaid line a plurality'ot series of im pulses an indicating device ateach of said outlying stations, a rotary selective switch at each ofsaid outlying stations having a single rotar arm and a plurality ofcontacts, means to drive said arm in response to the first series ofimpulses received from said central station, an electrical circuit ateach outlying station connected to a contact of said rotary switchcorresponding to the first digit of said designation number, meanscontrolled by current in said circuit to cause said driving means ofsaid rotary arm to be rte-actuated on the transmission of a subsequentseries of impulses, a second electrical circuit connecting a contactoteach of said rotary switches corresponding to the sum or" the digitsof said designation number to said indicating device, a springcontrolled pawl adapted to hold said rotary arm in position after eachseries of impulses, an electromagnetic releasing device to withdraw saidpawl and to restore said'rotary member to normal.

5. In a selective signalingsystem the combination of a central station,a plurality of outlying stations each having a designation number, acommon line'connecting said stations, means at said central station. totrans mit over said line a pluralityot series of impulses, an indicatingdevice at each of said outlying stations, a rotary selective switchat'eaoh of said outlying stations-having a sin le rotary arm and aplurality of contacts, means to'drive said arm in response to the firstseries of impulses received from said central station, an electricalcircuit at each outlyingstation connected to a contact of said rotaryswitch corresponding to the first digit of said designation number,means controlled by current in said Circuit to cause said driving meansof saidrotary arm to be re-actuated on the transmission of a subsequentseries of impulses, a second electrical circuit connecting a contact oreach of said rotary switches cor 'esponding to the sum of the digits ofsaid designation number to said indicating device, a spring controlled,

pawl adapted to hold said rotary member in position after the series ofimpulses and an electromagnetic releasing device to withdraw'said pawlon response of the station selected.

6. In a selective signaling system the combination of'a central station,a pluralityot outlying stations each having a designation number, acommon line connecting said stations, means at said central station totransmit over said line a plurality of series of current impulses, anindicating device at each of said outlying stations, arotary selectiveswitch at each of said outlying stations having a single rotary arm anda plurality of contacts, means including an electromagnet to drive saidrotary arm in response to the impulses received from said centralstation, a source of current, an electrical circuit connecting saidelectromagnet to said source of current and means to break said circuitautomatically upon said rotary arm coming to rest after the transmissionof the first of said series of impulses.

7. In a selective signaling system the combination of a central station,a plurality of outlying stations each having a designation number, acommon line connecting said stations, means at said central station totrans; mit over said line a plurality of series of impulses,anindicatingdevice at'each ofsaid outlying stations, a rotary selectiveswitch at each of said outlying stations having a single rotary arm anda plurality of contacts, means to drive saidarm in response to the firstseries ofimpulses received from said central station, an e ectricalcircuit atfeach outlying station connected to a Contact of said rotaryswitch corresponding to the first digit of said designation number,means controlled by current in said circuit to cause saiddriving meansof said rotary arm to be re-actuated on the transmission of a subsequentseries of impulses, a second electrical circuit connecting a contact ofeach of said rotary switches corresponding tothe sum of the digits ofsaid designation number to said indicating device, a. spring controlledpaw] adapted to hold said rotary arm in position magnetic releasingdevice upon the move-' ment oi said key into the speaking position.

'8. In a selective signaling system the combination of a centralstation, a plurality of outlying stations each having a designationnumber, a common line connecting said sta tions, means at said centralstation to transmit over said line a plurality of serles of imposes, anmdicating device at each of said outl in stations, a rotar selectiveswitch at each of said outlying stations having a single rotary arm anda plurality of contacts means to drive said arm in response to the firstseries of impulses received from said central station, an electricalcircuit at each outlying station connected to a contact of.

said rotary switch corresponding to the first digit of said designationnumber, means controlled by current in said circuit'to cause saiddriving means of said rotary arm to be re-actuated on the transmissionof a subsequent series of impulses, a second electrical circuitconnecting a contact of each of said rotary switches corresponding tothe sum of the digits of said designation number to said indicatingdevice, a tens bar included in said first electrical circuit, and aunits bar connected in said second electrical circuit, additional pairsof terminals, connecting links between the terminals of each pair, meansto connect one terminal of one pair to a predetermined switch contact ateach outlying station, means connected to the other terminal of saidpair to apply current to said driving means when said rotary arm comesto rest on the predetermined contact of said rotary switch, andconnecting means between said other pair of terminals and saidindicating device.

9. In a selective signaling system the combination of a central station,a plurality of outlying stations each having a designation number, acommon line connecting said stations, means at said central station totransmit over said line a plurality of series of current impulses, anindicating device at each of said outlying stations, a rotary selectiveswitch at each of said outlying stations, having a single rotary arm anda plurality of contacts, an" electromagnet to drive said rotary arm inresponse to the impulses received from said central station, a source ofcurrent, an electrical circuit connecting said electromagnet to saidsource of current, means to break said circuit automatically upon saidrotary arm coming to rest after the transmission of the first ofsai'dseries of impulses, a, tens bar, a connecting link between one of saidswitch contacls corrcsource to said electroinagnel When said r0-sponding to the first digit of said designation tary arm rests on saidcontact correspond 10 number and said tens bar, a relay having ing tothe first digit of said designation a coil element and a contactelement, a secnumber. 0nd source of current, a second electrical cir- InWitness whereof, I have hereunto signed cuil; including said connectinglink and the my name this 7th day of February 1921.

coil element of said relay and means con 4 I trolled by said relay toapply said second GEORGE WILLIAM FLYNN.

